北部湾二长棘犁齿鲷的时空分布特征

Tempo-spatial distribution of Evynnis cardinalis in Beibu Gulf

二长棘犁齿鲷(Evynnis cardinalis)作为北部湾主要经济鱼类之一,长久以来受过度捕捞的影响,其资源量发生较大波动,将对渔业生产和种群结构有较大影响。文章根据2014年~2015年近海渔业资源调查资料,应用生物量和个体数单位捕捞努力量渔获量(CPUE)综合分析该鱼种资源的季节变化和空间分布。结果表明该鱼种广泛分布于北部湾中国管辖海域内,四季的出现率均在86%以上。生物量和个体数CPUE有明显的季节变化,均表现为最高值在夏季(平均值分别为7.3 kg·h^(-1)和240.83尾·h^(-1)),而冬季最低(平均值分别为1.76 kg·h^(-1)和21.94尾·h^(-1))。从空间分布看,生物量和个体数CPUE高值区主要分布于北部湾20°N以北海域,而低值区则处于海南岛西部海域。近年来在该海域实施的资源养护措施已取得初步成效,相比于20世纪90年代,二长棘犁齿鲷的资源量有所恢复。但二长棘犁齿鲷生物学特征分析结果表明,体长200 mm或体质量80 g以上的群体比重总体偏低,种群低龄化和小型化问题仍较为严峻,需采取新的管理措施(增大最小网目和开捕体长),以降低捕捞强度,改善种群结构。

Evynnis cardinalis is one of the main commercial fish in Beibu Gulf, but its stocks fluctuated greatly resulting from longterm overfishing, which has significant effects on fishery production and population structure. Based on the offshore fishery resources survey during 2014 - 2015, the paper conducted a comprehensive analysis on seasonal variation and spatial distribution of E. cardinalis in Beibu Gulf by studying the catch per unit effort （ CPUE ） for biomass and number. The results suggest that E. cardinalis is widespread around Beibu Gulf with occurrence of over 86% for four seasons at present. Both CPUE for biomass and number showed obvious seasonal variation. The highest values in summer were 7.30 kg·h^-1 and 240. 83 ind·h^-1 averagely, respectively, but the lowest values in winter were 1.76 kg·h^-1 and 21.94 ind·h^-1 averagely, respectively. For spatial distribution, high CPUE for biomass and number mainly occurred in northern sea area of 20°N in Beibu Gulf, but low value occurred in western sea area of Hainan Island. Moreover, it is found that implementation of resource conservation has made achievements across Beibu Gulf in recent years. Compared with the situation in 1990s, the stock of E. cardinalis has recovered. However, the analysis of biological characteristics for E. cardinalis indicates that population whose body length over 200 mm or weight greater than 80 g only occupied a small proportion. Thus, low-age and miniaturization are still serious problems for E. cardinalis. Some measures, such as increasing the smallest size of mesh and catch body length, should be taken to reduce the fishing intensity and make improvement in population structure.